The present disclosure relates to a propulsion control system for controlling a marine vessel. Moreover, the present disclosure relates to a marine vessel. Further, the present disclosure relates to a method for controlling a marine vessel.
The present disclosure can be applied in arty type of marine vessel, such, as larger commercial ships or smaller vessels such as leisure boats and other types of water vehicles or vessels.
Although the present disclosure will be described with respect to a leisure boat, the present disclosure is not restricted to s particular vessel, but may also be used in other vessels such as a larger commercial ship.
Marine vessels of today may be equipped with a plurality of propulsion units for driving the vessel. The propulsion units may be controlled by a propulsion control system.
WO 2013/122516 A1 discloses a marine propulsion control system that is adapted to control a plurality of propulsion units of a marine vessel. The WO 2013/122516 A1 control system may for instance be adapted to control the propulsion units such that a pure sway motion of the vessel is obtained.
Although the WO 2013/122516 A1 control system is suitable for obtaining certain requested motions of the marine vessel hosting the control system, it would be desirable to increase the versatility of such control systems further.
It is desirable to provide a propulsion control system that can be used for controlling a propulsion unit set of a marine vessel in a versatile manner.
As such, one aspect of the present disclosure relates to a propulsion control system for controlling a marine vessel comprising a propulsion unit set which in turn comprises at least four propulsion units. The marine vessel comprises a longitudinal centre line and a transversal line. The transversal line extends in a direction perpendicular to the longitudinal centre line and also extends through the steering axis of the aftmost of the propulsion units. The vessel comprises four quadrants defined by the longitudinal centre line and the transversal line, wherein a first and a second quadrant are located on the same side of the longitudinal centre line. The propulsion control system is adapted to receive an input command from a vessel steering control arrangement.
According to the first aspect of the present disclosure, if the input command is indicative of a combined sway and yaw motion being desired, the propulsion control system is adapted to control the propulsion unit set such that:                each one of a first, a second, third and fourth propulsion unit of the propulsion unit set produces a thrust in a direction that forms an angle with the longitudinal centre line;        each one of a first, a second and a third propulsion unit of the propulsion unit set produces a thrust in a direction towards the first quadrant;        a fourth propulsion unit of the propulsion unit set produces a thrust in a direction towards the second quadrant, and        the magnitude of the thrust produced by each one of the first and the fourth propulsion unit is greater than the magnitude of the thrust produced by each one of the second and the third propulsion unit.        
The above control of the propulsion unit set implies that a motion control of the marine vessel in which a combined sway and yaw motion is obtained in a straightforward manner. Moreover, the control of the propulsion unit set as presented hereinabove implies that a change between a pure sway motion and a combined sway and yaw motion, and vice versa, can be obtained without necessarily have to shift gears of any one of the four propulsion units. This in turn implies the possibility to obtain a swift change between a pure sway motion and a combined sway and yaw motion.
The above possibility may for instance be desired when the marine vessel 10 is in a docking mode, i.e. when the marine vessel 10 is involved in a docking manoeuvre.
Optionally, the first quadrant is located aft of the transversal line such that each one of the first, second and third propulsion unit has a reverse gear selection when producing the thrust.
In an example where the propulsion unit is an outboard engine for instance, the maximum thrust producible when the propulsion unit has a reverse gear selection is generally lower than the maximum thrust producible when the propulsion unit has a forward gear selection. As such, with a configuration such as the one presented hereinabove, it may be straightforward to obtain comparable thrusts in the forward and rearward directions such that the sum of the thrusts results in a combined sway and yaw motion for instance.
Optionally, the propulsion control system is adapted to individually control each one of the first, second, third and fourth propulsion unit. An individual control implies an increased possibility to e.g. obtain a transition from a sway and yaw motion to a sway motion or vice versa.
A second aspect of the present disclosure relates to a marine vessel comprising a first, a second, a third and a fourth propulsion unit. The marine vessel further comprises a propulsion control system according to the first aspect of the present invention.
A third aspect of the present disclosure relates to a method for controlling a marine vessel comprising a propulsion unit set which in turn comprises four propulsion units. The marine vessel comprises a longitudinal centre line and a transversal line, the transversal line extending in a direction perpendicular to the longitudinal centre line and also extends through the steering axis of the aftmost of the propulsion units. The vessel comprises four quadrants defined by the longitudinal centre line and the transversal line, wherein a first and a second quadrant are located on the same side of the longitudinal centre line.
The method according the third aspect of the present disclosure comprises:                receiving instructions indicative of a combined sway and yaw motion being desired, and        controlling the propulsion unit set such that:                    each one of a first, a second, third and fourth propulsion unit of the propulsion unit set produces a thrust in a direction that forms an angle with the longitudinal centre line;            each one of a first, a second and a third propulsion unit of the propulsion unit set produces a thrust in a direction towards the first quadrant;            a fourth propulsion unit of the propulsion unit set produces a thrust in a direction towards the second quadrant, and            the magnitude of the thrust produced by each one of the first and the fourth propulsion unit is greater than the magnitude of the thrust produced by each one of the second and the third propulsion unit.                        
A fourth aspect of the present disclosure relates to a computer program comprising program code means for performing the steps of the third aspect of the present disclosure when the program is run on a computer.
A fifth aspect of the present disclosure relates to a computer readable medium carrying a computer program comprising program code means for performing the steps of the third aspect of the present disclosure when the program product is run on a computer.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.